Felix Felicis

Felix that has a lucky charm that lasts for twelve hours. However, this potion takes a year to make. Proffessor Horace Slughorn gave Harry Potter the lucky potion for finishing the potion by using the old copy that he borrowed form Proffessor Slughorn. That old copy turned out to be the Half Blood Prince's book.

The Half-Blood Prince was Severus Snape, old Potions teacher who hated Harry. He wanted to teach Defense from the Dark Arts for a very long time, and finally Dumbledore allowed him in Harry Potter's sixth year. Snape was the Head of Slytherin, and died in three hours before Voldemort, as Voldemort killed him before Harry killed him.